The present invention relates generally to a fossil fuel-fired home heating or cooling system that consumes minimal electrical power for operation and control.
The AC relay-based control scheme for home heating systems has not changed substantially since the early 1930s. Since 1945, major developments in home heating systems have consisted of adding additional components and safety mechanisms such as stack dampers and flame sensors. However, the control scheme has not been updated.
Heating systems typically have control schemes wherein most of the components in the heating system are activated or deactivated by closing or opening AC relay contacts. These electromagnetic switches close or open when the circuit supplying power to the magnetic coils within them are energized or de-energized. In gas-fired hydronic systems, the boiler control circuit coordinates the operation of the circulator pump, stack damper and gas valve. The zone valves, thermostats and boiler control circuits in these systems typically operate on non-lethal 24V AC power, which is obtained from 110/120V AC household power using a transformer.
In recent years, development in home heating systems has focused on improving the Annual Fuel Use Efficiency of the boiler or furnace, which considers only consumption of fossil fuel and not the electrical energy used by components in the system. Electric power demand of fuel-burning heating systems has consequently increased, such that today, a typical system consumes 20W on standby, as much as 2 kW during main burner ignition and 250-550W during normal hydronic boiler or hot-air furnace operation. Due to its high electricity demand, when utility power goes off, the typical heating system can operate only if an expensive back-up power system has been installed. Moreover, when building heating systems fail during the winter, the effects can be harmful to the health and safety of building occupants and the integrity of the building plumbing systems. To date, there has been no move to redesign the control system to try to reduce the electric power consumption of home heating system controls in order to address these problems with the prior art.
Additionally, there is no easy way to troubleshoot faults in conventional home heating systems. For example, if the blocked vent switch on the stack damper in a gas-fired heating system opens, the gas valve will close, but the stack damper will stay open and the circulator pump will stay on. Diagnosis of this problem is complicated because no error messages or indications are displayed anywhere in the system. Thus, conventional heating systems suffer from poor error detection capabilities.
U.S. Pat. No. 6,237,855 (Stickney et al.) describes a system for controlling a hydronic heating system with a DC power source. This system uses DC power as the primary source of electricity by having DC relays and separate DC pumps for each zone. But this system also uses DC-AC inverters and DC-DC converters, which have significant electrical losses associated with them. Thus, even though this system uses DC power, it does not redesign the control system so as to use microprocessors to control the heating system operation, to further reduce power consumption, or to provide enhanced system diagnostics.
Various microprocessor-based control systems have been developed for heating systems. Microprocessor-based systems described in U.S. Pat. Nos. 4,381,075 (Cargill et al.), and 4,844,335 (McKinley et al.) compare the temperature of the water in the boiler and the temperature of outside air to control the boiler water temperature. These systems concentrate on controlling the temperature of the boiler water but not the other control circuits in the system.
The microprocessor-based system described in U.S. Pat. No. 5,318,104 (Shah et al.) further utilizes a microprocessor-based controller for comparing the set temperature and the actual temperature for controlling the cycling of the heating/cooling plant. The microprocessor activates the heating/cooling plant based on which zone in the system requires the most heat/cooling (the zone of greatest thermal error).
The electronic boiler control unit described in U.S. Pat. No. 5,779,143 (Michaud et al.) combines several controls in one circuit, thus requiring no external wiring. The microprocessor for this hydronic heating system changes boiler water temperature in relation to the outside air temperature as well as the current boiler water temperature and operates zone valves based on a priority heating zone. Again, this system improves the seasonal efficiency of the boiler, but does not alter the control circuits for the other components in the system.
Finally, U.S. Pat. No. 5,515,297 (Bunting) describes a monitoring and diagnostic apparatus for an oil-only burner system, with three sensors that are able to detect and display errors in the operation of the burner thermostat, burner ignition transformer, and stack vent outside temperature. A microprocessor records and displays the data the three sensors measure for diagnosis of the operational history over a pre-selected time interval.
However, to date, no commercially available microprocessor-based control system for a home heating system has been designed to operate independently from the electric utility grid (AC power) by using DC power. In addition, no heating system incorporates the detection and display of errors in the heating system when they occur. Furthermore, no control system for a home heating system is capable of communicating with an external computer for purposes of data storage or error diagnosis.
Zone valves are used in hydronic heating and cooling systems to deliver hot or cold water to a particular area, or zone, of the entire area served by a heating or cooling system. Typically, the zone valve receives a contact closure signal from a thermostat, which causes the valve to open. Conventionally, a heat motor or an electric motor is turned on, and stays on to hold the valve open. The valve typically opens by driving an elastomeric diaphragm or ball away from a seat against a spring, or by holding a rotary valve, like a ball valve, open against a spring. When the thermostat contacts open, the motor circuit opens and the valve is returned to the closed position by a mechanical restorative device, typically a spring-return mechanism. Power must therefore be supplied to the valve whenever it has to be opened, making zone valves highly electrical energy inefficient. A typical valve is powered by a 24 volt AC power supply.
U.S. Pat. Nos. 5,131,623 and 5,540,414 (Giordani et al.) describe a zone valve where a motor driven actuator rotates a ball valve 90 degrees from closed to open position. When the motor is de-energized, the valve is returned to its normally closed position by a spring.
U.S. Pat. No. 6,186,471 (Genga et al.) describes a zone valve with a motor driven actuator that rotates a valve from a first position to a second position, such that the motor is only rotated when the valve changes position. At least one of the positions is a fail-safe position to which the valve will return if there is a loss of electrical power. As the valve turns, a sensor, as opposed to a mechanical switch, detects when the valve has reached a desired position and the motor is de-energized. However, the position of the valve is not known a priori without using the actuator to rotate the valve. The actuator provides a capacitive energy storage element that powers the motor in case of power failure.
Consequently, a need exists for a valve wherein (i) a motor turns the valve, and (ii) power to the motor is controlled using a sensing system that detects the position of the valve, and (iii) the position of the valve can be determined without rotating the valve. Such a scheme would be beneficial in enabling the development of remote indicators that detect and display the state of each zone valve in a heating system. In addition, if the state of each zone valve is known when power returns, then there is no need for any zone valve in a home heating system to move to a fail safe position upon power loss.
Additionally, no zone valve for a heating or cooling system using a rotary valve has been actuated using a DC power supply, a DC motor, and DC control components designed so as to use significantly less power than AC components to do the same tasks.
The low powered valve actuator described in U.S. Pat. No. 5,085,401 (Botting et al.) provides a complex mechanical device which creates a high mechanical (torque) ratio for turning a valve. The device increases the effective torque generated by a DC motor which is usually limited by its DC power source. This device provides high torque from a relatively low voltage source, necessarily at the expense of low rotational speed.
Another actuator producing high torque output for less electrical power is the electrically actuated flow diversion valve described in U.S. Pat. No. 5,226,454 (Cabalfin). In order to reduce electrical power consumption for a given torque output, the diverter valve includes a DC motor and gear reducer assembly. The actuator includes a built-in rectifier to convert AC input power to DC power to actuate the DC motor.
The prior art thus describes devices using low voltage DC power to operate a valve. However, these valves still require high torque for operation. Therefore, despite the fact that zone valves control flow but need not seal against high pressure, no prior art describes a DC operated rotary valve that does not require high torque to operate. Additionally, no prior art exists for a valve that indicates or reports its xe2x80x9copenxe2x80x9d, xe2x80x9cclosedxe2x80x9d or xe2x80x9cneither open nor closedxe2x80x9d positions independently of rotating the valve.
Thus, a need remained in the art, which is met by the present invention, for a device that increases the electrical efficiency and reliability of home heating or cooling systems by providing (i) a control system for a heating or cooling system that can operate independently of electrical utility power, (ii) a control system that provides better system diagnostics through increased error detection and display, (iii) a control system that can communicate with computers for data storage or error diagnosis, and (iv) a zone valve that uses DC control components and minimal DC power, and which detects the position of the valve without rotating the valve.
The present invention provides a device and a method for using minimal electrical power to control a heating or cooling system, thereby achieving off-grid operating capability. The present invention comprises a low-power DC microprocessor-based control system for a heating system that can operate with most conventional heating system components and provide better system diagnostics through increased error detection and display. The present invention further comprises a zone valve that is electromechanically actuated by a DC motor. The present invention does not compromise safety features inherent in conventional heating systems. In fact, with the improved error detection in the present invention, safety of the heating system has been increased. In this manner, the control system for a heating system has become more intelligent.
The present invention provides a microprocessor-based control system device for a heating or cooling system, wherein the control system device further comprises at least one of each of: a thermostat microprocessor, a zone valve microprocessor, and a boiler microprocessor that communicate with one another. Another embodiment of the present invention provides a microprocessor-based control system device for a heating or cooling system, wherein the control system device further comprises: thermostat microprocessor, zone damper microprocessor, and furnace microprocessor that communicate with one another.
A preferred embodiment of the invention provides a control system that detects and displays errors in operation of the system. The invention includes a control system that saves information on power consumption and temperatures in each zone such that improved heating control algorithms can be implemented in the system. Additionally, the control system may display the level of power it is consuming.
In the preferred embodiments of the invention, the control system microprocessors can communicate information to each other and also to the outside world via an interface with a computer.
Another object of the present invention provides an electrically operated actuator for a zone valve in a heating or cooling system, wherein the zone valve further comprises: a DC motor coupled to the valve such that rotation of the motor shaft corresponds to a change in the position of the valve; sensor system which is able to detect the state of the valve, whether it is open, closed, or neither open nor closed; and microprocessor which controls power delivery to the motor based on output of the sensor system.
A preferred embodiment of the invention further comprises: the motor coupled to the zone valve stem by means of gears, wherein the rotation of the motor shaft rotates the valve stem element by 90 degrees in order to change state from open to closed or closed to open. In a preferred embodiment, the valve is a ball valve. In addition, in a preferred embodiment, the actuator includes a means for disengaging the gears to enable manual operation of the valve without affecting normal sensing or reporting of valve position.
The preferred embodiment of the sensor system of the present invention further comprises; two or more sensors, each sensor having two outputs, which detect the position of one or more indicators coupled to the valve stem, such that at least one output state of the sensors corresponds exactly to the open state, at least one output state of the sensors corresponds exactly to the closed state, and at least one output state of the sensors corresponds to neither the open or closed state. In the preferred embodiment of the present invention, the sensors are optical sensors placed 90 degrees apart, whereby the sensors detect one or more cavities or other irregularities on the surface of the gear coupled to the valve stem.
A microprocessor activates the motor when the desired state of the valve is not indicated by the sensors and deactivates the motor when the desired state is indicated. In the preferred embodiment, the microprocessor communicates the state of the valve to other control components of the heating or cooling system and optionally to a computer and/or an external display. As provided in the preferred embodiment, the microprocessor detects if the actuator is unable to rotate the valve to the desired state and indicates such a failure with a buzzer or other built-in indicator, or by communication to other components of the heating or cooling system, a computer, or an external display.
In another preferred embodiment, a method is provided for controlling a heating system comprising: quantifying the room and user-defined set temperatures in a zone through a thermostat microprocessor; communicating the temperatures to a separate zone valve microprocessor; sending the room and user-defined temperatures to a boiler circuit microprocessor; controlling the zone valve position based on the room and user-defined set temperatures; sending information regarding the position of the zone valve to the boiler circuit microprocessor; saving the temperature data; operating a stack vent damper, circulator pump, and gas valve; detecting errors in the boiler components; detecting errors in any zone valves; displaying errors on one or more boiler audio-visual displays, and transmitting the data to a computer. In the preferred embodiment, the system is operated using a low-voltage DC power supply or transformed and rectified AC voltage supply. The preferred embodiment further provides for the display of detected errors on an audio-visual display.
In yet another preferred embodiment, a method is provided for controlling a heating system comprising: quantifying the room and user-defined set temperatures in a zone through a thermostat microprocessor; communicating the temperatures to a separate zone damper microprocessor; sending the room and user-defined temperatures to a furnace circuit microprocessor; controlling the zone damper position based on the room and user-defined set temperatures; sending information regarding the position of the zone damper to the furnace circuit microprocessor; saving the temperature data; operating a stack vent damper, blower, and gas valve; detecting errors in the furnace components; detecting errors in any zone dampers; displaying errors on one or more furnace audio-visual displays, and transmitting the data to a computer. In the preferred embodiment, the system is operated using a low-voltage DC power supply or transformed and rectified AC voltage supply. The preferred embodiment further provides displaying the detected errors on an audio-visual display.